Machine tool



E. P. BUFQFRELL MACHINE TOOL Originl Filed May 12, 1952 3 Sheets-Sheet lINVENT OR.

BY .Zn mb flm/ ATT RNEY5 E. P. BURRELL Z QJS MACHINE IOOL Original FiledMay 12, 1932 3 Sheets-Sheet 2 INVENTOR. E0 W Q/QD PEi EEELL ATTQRNEYSApril 2%, 1%36 E, P BURRELL ZfiBQflQ-fi MACHINE TOOL Original Filed May12, 1952 3 Sheets-Sheet 5 BY W ATTORNEY5 Patented Apr. 28, 1936 UNITEDSTATES PATENT OFFICE MACHINE TOOL Original application May .12, 1932,vSerial No. 610,904. Divided and thisapplication June 21,

1935, Serial No. 27,739

4 Claims.

This invention relates to a machine tool and particularly to a systemfor controlling the temperature of those parts of a machine tool whichare subject to temperature changes during the 5 operation of themachine.

The present application is a division of my copending application SerialNumber 610,904, filed May 12, 1932.

Heretofore thequality of the cutting tools used in machine tools hasprecluded the use of high operating speeds for the machine since thetools would break down during the cutting engagement with the work. Theslow operating speeds under the old practice did not produce in thevarious operative parts of the machine sufiicient heat to be detrimentalto the machine or to said parts. On the other hand the high quality ofthe cutting tools now used in machine tools permits the machines to beoperated at high operating speeds, wherefore the various moving partsand the-bearings therefor of the machine are subjected to detrimentallyhigh temperatures.

An object of the invention is to provide in a machine tool efficient andeffective means for controlling the temperature of certain moving partsof the machine and the supports therefor that are subject to temperaturechanges during the operation of the machine.

Another object is to provide means in a machine tool for maintaining thecorrect relationship between various moving parts of the machine andtheir supports that are subject totemperature changes during operation,to the end that the eiiiciency and accuracy of the machine will beretained.

Another object is to provide in a machine tool passageways in themachine through which fluid is circulated and which passagewayssubstantially surround certain moving parts of the machine and theirsupports, whereby the circulating fluid will control the temperature ofsaid parts and supports.

Another object of the invention is to provide in a machine tool, havingcertain moving parts which together with their supports are subject totemperature changes during operation, means for circulating fluid inthermal transferring relationship to said parts and supports in suchvolume, velocity and temperature as to maintain said parts and supportssubstantially at a desired temperature.

A further object is to provide in a machine tool wherein the workspindle constitutes the rotor spindle of the operating motor, passage-Ways surrounding the bearings at said spindle and through which fluidcan be circulated for controlling the temperature of the bearings.

A still further object is to provide in a machinetool means forpreventing distortion of the bearings of moving parts of the machine dueto 5 temperature changes and which consists in circulating fluid in thepassageways surrounding the bearings, thus preventing misalignmentbetween the bearings for said parts.

A further object is to provide in a machine 10 tool wherein the workspindle constitutes the rotor spindle of the main operating motor,passageways surrounding the bearings for said spindle and communicatingwith a chamber housing the motor control unit, wherefore fluid 15 iscirculated through said chamber, then through said passageways andaround the bearings to control the temperature of the bearings and themotor control unit.

Further and additional objects and advantages 20 appear hereinafterduring the following detailed description of an embodiment of theinvention which is illustrated in the accompanying drawings, whereinFig. 1 is a fragmentary front elevational view 25 of a machine toolembodying the present invenion.

Fig. 2 is an end elevational view of the machine shown in Fig. 1 and istaken from the left hand end thereof. 30

Fig. 3 is a vertical sectional view on an enlarged scale takensubstantially on line 3-3 of Fig. 2 looking in the direction of thearrows with the motor control unit removed.

Fig. 4 is a vertical transverse sectional view 35 taken substantially-online 44 of Fig. 3 looking in the direction of the arrows, the motor andthe motor control unit being shown in elevation.

Fig. 5 is an irregular vertical transverse sectional view takensubstantially on line 5-5 of 40 Fig. 3 looking in the direction of thearrows.

Although the invention contemplates the provision of means in a machinetool for controlling the temperatures of various moving parts of themachine and their supports which are subject to temperature changes inoperation, the embodiment of the invention illustrated in theaccompanying drawings and described herein will relate, by way ofillustration, to the provision of means in the head of the machine forcontrolling 50 the temperature of the bearings for the work spindle,which in this case is also the rotor spindle for the operating motor, aswell as for controlling the temperature of the motor control unitlocated in the bed beneath the head, but it should be understood thatthe invention is applicable for controlling the temperature of othermoving parts of the machine together with the supports therefor.

The employment of high grade cutting tools as practiced at the presenttime in machine tools has necessitated and permitted high work spindlespeeds, which results in greatly increasing the degree of heat developedby the various operative parts of the machine and their supports. Inaddition the use of higher grade cutting tools per mits deeper andheavier cuts to be taken in the work, resulting in greater thrustbetween the tools and work, with a consequent increase in the heatdeveloped in the bearings for the spindle during the operation of themachine. The con tinuous operation of machine tools under the abovementioned conditions and for long periods of time brings aboutdistortion in the diiferent parts of the machine because of the amountof heat developed in the bearings therefor, and unless this heat is keptsubstantially at room temperature or at some other desired determinabletemperature the accuracy and efficiency of the machine will be destroyeddue to the changed relationship between the parts.

The present invention contemplates the provision of means in a machinetool which will maintain the various moving parts of the machine andtheir supports or bearings, as well as the elements controlling thesame, at the proper temperature thereby eliminating distortion,retaining the accuracy and efficiency of the machine and reducing to aminimum the wear occasioned in such parts during their operation.

The present invention is embodied in a machine tool wherein the workspindle constitutes the rotor spindle of an electric motor housed in thehead of the machine and forming the driv ing motor for the spindle. Themachine tool illustrated comprises a bed I 0 having ways II and a. headl2 provided with a cover 13. The head I2 is formed with ends walls l4and I5 and with intermediate walls Hi and IT, said walls formingpassageways A and B surrounding the bearing supports l8 and I9 formed ininwardly extending portions integral with the walls l4 and I5 andconnected to the intermediate walls l6 and I! by circumferentiallyspaced ribs 20 and 2|. The passageways A and B extend downwardly belowthe head and into the bed and are in communication by means of openingsin the walls l6 and I! with a chamber C which houses the controller unit22 for the motor, see Figs. 3 and 4. The passageway A at its lower endis in communication with the atmosphere through an opening A formed inthe wall l4. Likewise it will be noted that the chamber C is incommunication with the atmosphere through the opening- A' and an openingformed in the bottom wall of the chamber and forming a continuation ofthe opening in the wall Hi. The upper wall of the compartment C isprovided with a small opening C directly communicating with the motorchamber wherein is located the stator for the motor. The work spindlewhich, it will be remembered is also the rotor spindle for the motor, isindicated at 23 and is rotatably mounted in bearings 24 and 25 located,respectively, in the bearing supports l8 and I9 and in the presentinistance being in the form of anti-friction bearngs.

The intermediate walls l6 and I1 and the walls of the head cover l3adjacent the bearing supports l8 and I9 and inwardly thereof areprovided with funnel-shaped portions 26 and 21 for the purpose ofdirecting the fluid passing through the passageways A and B and aroundthe bearing supports inwardly of the head. The spindle 23 intermediatethe funnel-shaped portions 26 and 21' is provided with a rotor 28arranged to rotate within the stator 29 of the motor, said stator beingsecured to the front and rear walls of the motor chamber or head bymeans of suit able securing bolts as indicated at 30 in Fig. 4. The workspindle or rotor spindle 23 is provided intermediate the rotor 28 andthe funnel-shaped portions 26 and 21 with fan blades 3|, so positionedand shaped as to throw fluid radially outwardly when the rotor isrotating. An opening is provided between the securing points 30 for thestator which forms a passageway 32 connecting the spaces surrounding theopposite ends of the stator. The head cover l3 which is arranged overthe stator is provided in its front and rear walls with louvre openings33, see Fig. 4. It will be seen that when the work spindle is rotatingduring the operation of the motor the fan blades 3| act to force thefiuid or air radially outwardly with respect to the spindle and throughthe louvre openings 33, see arrows in Fig. 4. This forcing of the fluidor air outwardly of the motor chamber in the head through the louvreopenings produces a suction which results in air, at room temperature,being drawn through the opening A into the passage A and into thecontrol unit chamber C from which latter chamber after passing aroundand across the motor control unit 22 it passes through the opening inthe wall I! into the passageway B and through the opening 0' into themotor chamber, as indicated by the arrows in Fig. 3. The air drawn intothe passageway A circulates completely around and against the bearingsupport l8, after which it passes between the ribs 20, through thefunnelshaped portion 25 into the motor chamber and the interior of thestator. Similarly the air drawn into the passageway B circulatescompletely around and against the bearing support l9 before it passesbetween the ribs 2| through the funnel-shaped portion 21 and into themotor chamber and the interior of the stator.

It will be remembered that a portion of the air drawn into chamber Cpasses through the opening C and into the motor chamber and through thepassageway 32 to the opposite sides of the motor stator. The air at roomtemperature passing through the passageways A and B and circulatingcompletely around and against the bearing supports I8 and I9 and beforereaching the motor chamber acts to maintain the temperature of the workspindle bearings 24 and 25 substantially at room temperature despitehigh operating speeds and increased end thrust of the work spindle, thuspreventing distortion of said bearings and supports and therebymaintaining an accurate alignment of the bearings, supports and workspindle with relation to each other and to the other parts of themachine.

It will also be noted that the air at room temperature is drawn into thechamber C and circulates over and around the motor control unit 22before said air passes into the motor chamber or into the passageway B,and thus heating of the control unit is prevented. In addition it willbe noted that after the air at room temperature has circulated about andcooled the bearings and their supports and the motor control unit and isthen drawn into the motor chamber, it will have the additional andincidental function of circulating through the motor chamber and coolingthe motor.

It will be understood, of course, that various spindle speeds may beimparted to the work spindle 23 by means of the motor control unit 22which controls the speed of operation of the motor, which unit isoperated by the stop, forward and. reverse lever 35 and the speedcontrol lever 36 located at the front of the machine.

In consideration of the fact that in a machine embodying the presentinvention the bearings for the work spindle can be maintainedsubstantially at room temperature or at any other desired anddeterminable temperature even though the work spindle is rotating athigh operating speeds and is subjected to great end thrusts due to thetools taking heavier cuts, it should be noted that the machineillustrated herein can be successfully operated at a work spindle speedof 3600 R. P, M. as indicated in Fig. 1 without in any way lowering theefficiency, destroying the accuracy of the machine or injuring,misaligning or distorting the bearings for the work spindle.

Although a single embodiment of the present invention has beenillustrated and described herein it should be understood that theinvention is susceptible of various modifications and adaptations withinthe scope of the appended claims.

Having thus described my invention I claim:

1. In a machine tool having a head provided with spaced bearings and abed provided with a way, the axes of said bearings and said way beingarranged in exact parallel relationship, said head having wall portionsdefining passageways substantially surrounding said bearings, a work ortool spindle mounted in said bearings, fan blades carried by saidspindle and creating a circulation of air through said passageways andaround said bearings during the rotation of the Work or tool spindle tocontrol the temperature of said bearings and to prevent distortiontherein and a variation in the relationship of the way and bearings, andmeans for rotating said work or tool spindle.

2. In a machine tool having a head provided with spaced bearings and abed provided with a way, a work or tool spindle mounted in saidbearings, said head having wall portions defining passagewayssubstantially surrounding said bearings, fan members carried by saidwork or tool spindle for circulating air through said passageways andaround said bearings during the rotation of the work or tool spindle,and a motor mounted on said work or tool spindle.

3. In a machine tool having a head provided with bearings and a bedprovided with a way, said head including end walls and walls arrangedintermediate said end walls, certain of said intermediate walls formingwith said end walls passageways which substantially surround saidbearings, said last named intermediate walls having funnel-shapedopenings extending inwardly of the head and placing said passageways incommunication with the interior thereof, a work or tool spindle mountedin said bearings and extending through said funnel-shaped openings, fanmembers carried by said tool or work spindle and arranged in theinterior of the head for drawing air through said passageways and aroundsaid bearings and into the interior of the head, and means for rotatingsaid work or tool spindle.

4. In a machine tool having a head and a bed provided with a way, saidhead including end walls and walls located intermediatesaid end wallsand forming a plurality of chambers one of which houses a motor controlunit, certain of said second named walls forming with said end wallspassageways communicating with said chambers,

bearings located in said passageways, a work or tool spindle mounted insaid bearings, fan members carried by said work or tool spindle inanother of said chambers, and a motor for rotating said work or toolspindle whereby fluid will be circulated through said passagewayscompletely around and against said bearings and through said chambersand over said control unit.

EDWARD P. BURRELL.

